A primary sternal tumor is rare, and it is difficult to make an accurate diagnosis. We herein report a case of intraosseous schwannoma of the sternum, which was associated with various difficulties in regard to making an accurate preoperative diagnosis. A 38-year-old woman underwent a surgical resection for a sternal tumor. Preoperative radiologic images showed a well-defined, dumbbell-shaped and solid nodule in her sternum. However, a definitive diagnosis could not be obtained before the operation. The pathologic findings of the resected specimen revealed schwannoma, Antoni type A. No recurrence has been observed during her postoperative course.